Kurarinone promotes TRAIL-induced apoptosis by inhibiting NF-kappaB-dependent cFLIP expression in HeLa cells

This study was designed to investigate the effects of the prenylated flavonoid kurarinone on TNF-related apoptosis inducing ligand (TRAIL)-induced apoptosis and its underlying mechanism. A low dose of kurarinone had no significant effect on apoptosis, but this compound markedly promoted tumor cell death through elevation of Bid cleavage, cytochrome c release and caspase activation in HeLa cells treated with TRAIL. Caspase inhibitors inhibited kurarinone-mediated cell death, which indicates that the cytotoxic effect of this compound is mediated by caspase-dependent apoptosis. The cytotoxic effect of kurarinone was not associated with expression levels of Bcl-2 and IAP family proteins, such as Bcl-2, Bcl-xL, Bid, Bad, Bax, XIAP, cIAP-1 and cIAP-2. In addition, this compound did not regulate the death-inducing receptors DR4 and DR5. On the other hand, kurarinone significantly inhibited TRAIL-induced IKK activation, IkappaB degradation and nuclear translocation of NF-kappaB, as well as effectively suppressed cellular FLICE-inhibitory protein long form (cFLIPL) expression. The synergistic effects of kurarinone on TRAIL-induced apoptosis were mimicked when kurarinone was replaced by the NF-kappaB inhibitor withaferin A or following siRNA-mediated knockdown of cFLIPL. Moreover, cFLIP overexpression effectively antagonized kurarinone-mediated TRAIL sensitization. These data suggest that kurarinone sensitizes TRAIL-induced tumor cell apoptosis via suppression of NF-kappaB-dependent cFLIP expression, indicating that this compound can be used as an anti-tumor agent in combination with TRAIL.

Expression of cellular FLICE inhibitory proteins in peripheral blood B lymphocytes in patients with systemic lupus erythematosus / 中华皮肤科杂志

Objective To study the expression of cellular FLICE inhibitory proteins(c-FLIP)in peripheral blood B lymphocytes in patients with systemic lupus erythematosus (SLE)and its correlation with clinical features.Methods Blood samples were obtained from 53 patients with SLE and 30 normal human controls.Flow cytometry and ELISA were performed to measure the expression of c-FLIP in pefipheral blood B lymphocytes and serum levels of IL-4 and IL-10,respectively.Relevant laboratory examinations were carried out for these patients.SLE disease activity index(SLEDAI)score was calculated for patients.Results The positivity rate of c-FLIP in B lymphocytes was 3.11%±0.70%in 18 patients with active SLE.significantly higher than that in 35 patients with inactive SLE (0.78%±0.28%)and normaI controls(0.68%±0.12%),while no statistical difierence was found between inactive patients and controls(t=1.56,P＞0.05).In SLE patients,the expression of c-FLIP showed a positive correlation with SLEDAl score(r=0.96.P＜0.05),erythrocyte sedimentation rate(r=0.96,P＜0.01),serum level of C reactive protein(r=0.92.P＜0.01)and the titer of antinuclear antibodies(r=0.86,P＜0.01),whereas in 36 patients with leucopenia.a negative correlation was noticed between white blood cell count and the expression level of c-FLIP(r=-0.94,P＜0.0 1).The 23 patients with lupus nephritis had a higher level of c-FLIP than those without lupus nephritis(3.04%±1.09%vs 1.76%±1.09%,t=4.23,P＜0.05).Additionally.the expression of c-FLIP positively correlated with the serum level of IL-4 and IL-10(r=0.80,0.89.respectively,both P＜0.01).Conclusions In patients with active SLE,the expression of c-FLIP is upregulated in peripheral blood B lymphocytes,and positively correlated with the severity of SLE as well as the serum level of IL-4 and IL-10.The upregulation of c-FLIP in B cells might play a certain role in deficient apoptosis or clearance of activated B cells in SLE.